1. Field of the Invention
The present invention relates to a method and an engineering system for configuring and/or operating an automation device. In particular, the present invention relates to a method and an engineering system for configuring an/or operating an automation device with a master unit and at least one slave unit that can be connected to the master unit via a bus.
2. Description of Related Art
An automation device with so-called “decentralized peripherals” is known from the Siemens Catalog ST 70, Chapter 6, 2001 Edition, which is incorporated herein by reference. These “decentralized peripherals” are provided for decentralized solutions to automation tasks in production engineering, process engineering and systems control engineering. These decentralized peripherals usually include different peripheral devices with a number of slave modules, which are connected to a master unit via a bus. The master unit is usually a master module, which is a component of a powerful programmable controller having at least one CPU and further functional modules to solve complex automation tasks.
Actuators and/or sensors can be connected to the slave modules of a slave unit. Peripheral process input data transmitted by the sensors can be stored in the slave units. Moreover, the slave units can supply the actuators with peripheral process output data, which the master unit transmits to the slave units. An essential task of the master unit, on the one hand, is to transmit the peripheral process input data as an image to a higher-level processing unit of a programmable controller and, on the other hand, to process the image of the peripheral process output data supplied to the master unit by the higher-level processing unit and then to transmit this processed peripheral process output data to the slave units in the form of peripheral process output data. The higher-level processing unit cyclically processes the image of the peripheral process input data and that of the peripheral process output data during a processing time interval. This processing time interval (processing cycle) is essentially coordinated with a master access interval (master cycle) of the master unit. During this master access interval, the master unit performs read and/or write accesses to all of the slave units that are connected to the bus during an open loop control.
The master unit cyclically transmits to each slave unit the peripheral process output data associated with the corresponding slave units, such that the master access interval is essentially determined by the number of slave units connected to the bus. In response to the transmission of the peripheral process output data, each slave unit performs a write access to the bus during a slave-specific slave access interval, in order to transmit its peripheral process output data to the master unit. The length of the master access interval essentially depends on the number of the slave units connected to the master unit. The slave units themselves monitor their own slave access intervals. In the event that a slave unit is not accessed within its slave access interval, which indicates that peripheral process outputs of this slave unit are no longer addressed, that slave unit switches its peripheral process outputs to a safe state.
The number of the slave units that can be connected to the master unit is configured using, e.g., an engineering system, which is known from the Siemens Catalog ST PCS 7, Chapter 1, 2001 Edition, which is incorporated herein by reference. The number of the slave units to be configured depends on the control task to be solved.
It may occur, for example, that due to changes in the control task to be solved, the automation device must be expanded by an additional slave unit. This means that this additional slave unit must be newly configured such that the master access interval and the respective slave access intervals are respectively increased to accommodate for the additional slave unit. This is time-consuming, particularly because the new configuration must be tested prior to any open loop control operation.